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  Anatomic Abstracts

 

 

 

 

February 2012

Editors:
Michael Cibull, MD
Thomas Cibull, MD
Rouzan Karabakhtsian, MD

Investigation of MDM2-CDK4 immunohistochemical expression in osteosarcomas and other lesions Investigation of MDM2-CDK4 immunohistochemical expression in osteosarcomas and other lesions

Low-grade osteosarcoma is a rare malignancy that may be subdivided into two main subgroups—parosteal osteosarcoma and low-grade central osteosarcoma—based on its location relative to the bone cortex. The malignancies have a similar histological appearance that is characterized by spindle cell stroma with low-to-moderate cellularity and well-differentiated anastomosing bone trabeculae. Low-grade osteosarcomas have a simple genetic profile with supernumerary ring chromosomes comprising amplification of chromosome 12q13-15, including the cyclin-dependent kinase 4 (CDK4) and murine double-minute type 2 (MDM2) gene region. Low-grade osteosarcoma can be confused with fibrous and fibro-osseous lesions, such as fibromatosis and fibrous dysplasia, on radiological and histological findings. The authors investigated MDM2-CDK4 immunohistochemical expression in a series of 72 low-grade osteosarcomas and 107 fibrous or fibro-osseous lesions of the bone or paraosseous soft tissue. They also evaluated the MDM2-CDK4 amplification status of low-grade osteosarcoma by comparative genomic hybridization array in 18 cases. MDM2 amplification status was evaluated by fluorescence in situ hybridization (FISH) or quantitative real-time polymerase chain reaction (RT-PCR) in 31 cases of benign fibrous and fibro-osseous lesions. MDM2-CDK4 immunostaining and MDM2 amplification by FISH or quantitative RT-PCR were investigated in a control group of 23 cases of primary high-grade bone sarcoma, including 20 conventional high-grade osteosarcomas, two pleomorphic spindle cell sarcomas/malignant fibrous histiocytomas, and one leiomyosarcoma. The results showed that MDM2 or CDK4 immunoreactivity, or both, was present in 89 percent of low-grade osteosarcoma specimens. All benign fibrous and fibro-osseous lesions and the tumors of the control group were negative for MDM2 and CDK4. These results were consistent with the MDM2 and CDK4 amplification results. The authors concluded that immunohistochemical expression of MDM2 and CDK4 is specific and provides sensitive markers for the diagnosis of low-grade osteosarcomas, helping to differentiate them from benign fibrous and fibro-osseous lesions. This is particularly true in cases with atypical radio-clinical presentation or limited biopsy samples, or both.

Dujardin F, Binh MB, Bouvier C, et al. MDM2 and CDK4 immunohistochemistry is a valuable tool in the differential diagnosis of low-grade osteosarcomas and other primary fibro-osseous lesions of the bone. Mod Pathol. 2011;24:624–637.

Correspondence: Dr. G. de Pinieux at depinieux@med.univ-tours.fr
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Distinguishing cutaneous squamous cell carcinoma from actinic keratosis and normal skin Distinguishing cutaneous squamous cell carcinoma from actinic keratosis and normal skin

Actinic keratosis is widely believed to be a neoplastic lesion and a precursor to invasive squamous cell carcinoma. However, there has been debate about whether actinic keratosis is squamous cell carcinoma and should be treated as such. Because the clinical management and prognosis of patients is widely held to be different for each of these lesions, the authors set out to identify unique gene signatures using DNA microarrays to distinguish between normal skin, actinic keratosis, and squamous cell carcinoma, and to examine the molecular pathways of carcinogenesis involved in the progression from normal skin to squamous cell carcinoma. The authors obtained formalin-fixed and paraffin-embedded blocks of skin: five normal skins (pooled), six actinic keratoses, and six squamous cell carcinomas. They extracted and amplified the RNA. The labeled targets were hybridized to the Affymetrix human U133plus 2.0 array and the acquisition and initial quantification of array images were performed using the GCOS (Affymetrix). Subsequent data analyses were performed using the DNA-Chip Analyzer (dChip) and Partek Genomic Suite 6.4. Significant differential gene expression (greater than two-fold change; P<0.05) was seen with 382 differentially expressed genes between squamous cell carcinoma and normal skin, 423 differentially expressed genes between actinic keratosis and normal skin, and nine differentially expressed genes between actinic keratosis and squamous cell carcinoma. The authors concluded that the differentially expressed genes offer the possibility of using DNA microarrays as a molecular diagnostic tool to distinguish between normal skin, actinic keratosis, and squamous cell carcinoma. Furthermore, the differentially expressed genes and their molecular pathways potentially could be used as prognostic markers or targets for future therapeutic innovations.

Ra SH, Li X, Binder S. Molecular discrimination of cutaneous squamous cell carcinoma from actinic keratosis and normal skin. Mod Pathol. 2011;24(7):963–973.

Correspondence: Dr. S. Binder at sbinder@mednet.ucla.edu
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Molecular clustering based on ER-alpha and EIG121 predicts survival in select high-grade carcinomas Molecular clustering based on ER-alpha and EIG121 predicts survival in select high-grade carcinomas

The use of immunohistochemistry to assess estrogen receptor expression has yielded inconsistent results as a prognostic indicator in ovarian carcinoma. In breast and endometrial carcinomas, panels of estrogen-induced genes have shown improved prognostic capability over the use of estrogen receptor immunohistochemistry alone. Overexpression of estrogen-induced genes is associated with better prognosis in breast and endometrial cancers. The authors hypothesized that analysis of a panel of estrogen-induced genes can predict outcome in ovarian carcinoma and potentially differentiate between tumors of varying hormonal responsiveness. They studied 83 patients from a cohort of 219 women who underwent ovarian cancer surgery between 2004 and 2007. All of the patients had advanced stage ovarian/primary peritoneal high-grade serous carcinoma and underwent primary surgical debulking followed by adjuvant treatment with platinum and taxane agents. The expression of ER-α and six genes known to be induced by estrogen in the female reproductive tract—EIG121, sFRP1, sFRP4, RALDH2, PR, and IGF-1—was measured using quantitative reverse-transcriptase polymerase chain reaction. Unsupervised cluster analyses were used to categorize patients as high or low gene expressors. The authors compared gene expression results with those for estrogen receptor immunohistochemistry. They compared clusters using X2 analyses and evaluated survival outcomes using Cox proportional hazards models. The median followup time was 38.7 months (range, 1–68 months). A cluster defined by EIG121 and ER-α segregated tumors into distinct groups of high and low gene expressors. Shorter overall survival was associated with high gene expression (hazard ratio, 2.84 [1.11–7.30]; P=0.03), even after adjusting for other covariates. The authors found no difference in estrogen receptor immunohistochemistry expression between gene clusters. They concluded that, unlike with other hormonally driven cancers, high expression of ER-α and EIG121 predicts shorter overall survival in patients with high-grade serous ovarian carcinoma. Such a biomarker panel potentially may be used to guide management with estrogen antagonists in this patient population.

Schlumbrecht MP, Xie SS, Shipley GL, et al. Molecular clustering based on ERα and EIG121 predicts survival in high-grade serous carcinoma of the ovary/peritoneum. Mod Pathol. 2011;24:453–462

Correspondence: Dr. R. R. Broaddus at rbroaddus@mdanderson.org
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Assessment of IgG4 plasma cells in inflammatory myofibroblastic tumor Assessment of IgG4 plasma cells in inflammatory myofibroblastic tumor

Inflammatory myofibroblastic tumor is a rare mesenchymal neoplasm that harbors an anaplastic lymphoma kinase (ALK) gene rearrangement in the majority of cases. It is composed of fibroblastic-myofibroblastic cells with a characteristic inflammatory infiltrate that consists predominantly of plasma cells. In contrast, IgG4-related sclerosing disease is a recently described multisystem disorder with a histological appearance similar to inflammatory myofibroblastic tumor. The plasma cell infiltrate is characteristic in IgG4-related sclerosing disease and has been studied as a tool to render this diagnosis. Histologically, the two disorders overlap, although there are significant clinical differences. The authors conducted a study to analyze the histological appearance of 36 inflammatory myofibroblastic tumors, compare them with IgG4-related sclerosing disease, and assess the plasma cell profile using immunohistochemistry to determine the range and proportion of IgG4 plasma cells. The majority of patients were children and young adults who primarily had solitary masses and had no clinical manifestations of IgG4-related sclerosing disease. ALK-1 positivity was present in 23 cases (64 percent). None of these cases showed obliterative phlebitis or prominent lymphoid aggregates. Of 36 inflammatory myofibroblastic tumors, 15 cases showed an IgG4/IgG ratio of at least 0.10, a cutoff described in the literature as supportive of IgG4-related sclerosing disease, and up to 33 IgG4-positive plasma cells per high-power field, indicating a mild-to-moderate increase as compared with IgG4-related sclerosing disease. The diagnostic recognition of inflammatory myofibroblastic tumor is based on clinicopathological features and diagnostic adjuncts, such as ALK-1 reactivity and genetic tests. Although inflammatory myofibroblastic tumor and IgG4-related sclerosing disease are distinct entities, a subset of inflammatory myofibroblastic tumors exhibit an IgG4/IgG ratio that is within the range for IgG4-related sclerosing disease. Therefore, this ratio alone cannot be used to reliably discriminate between these two entities. Other clinical and pathologic features must be considered.

Saab ST, Hornick JL, Fletcher CD, et al. IgG4 plasma cells in inflammatory myofibroblastic tumor: inflammatory marker or pathogenic link? Mod Pathol. 2011;24:606–612.

Correspondence: Dr. C. M. Coffin at cheryl.coffin@vanderbilt.edu
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Distinction between primary adrenal cortical lesions and CC-RCC Distinction between primary adrenal cortical lesions and CC-RCC

Diagnosing metastatic clear cell renal cell carcinoma (CC-RCC) can be difficult because of its morphologic heterogeneity and the increasing use of small image-guided biopsies that yield scant diagnostic material. This is further complicated by the degree of morphologic and immunophenotypic overlap with nonrenal neoplasms and tissues, such as adrenal cortex. The authors conducted a study in which they examined the immunoprofile of 63 adrenal cortical lesions, which included 54 cortical neoplasms, and compared them with 185 metastatic CC-RCCs using traditional and novel antibodies. The traditional antibodies were anticalretinin, CD10, antichromogranin, antiepithelial membrane antigen, anti-inhibin, antimelan-A, anticytokeratins (AE1/AE3 and AE1/CAM5.2), antirenal cell carcinoma marker, and antisynaptophysin. The novel antibodies were anticarbonic anhydrase-IX, antihepatocyte nuclear factor-1β, antihuman kidney injury molecule-1 (hKIM-1), anti-PAX-2, anti-PAX-8, antisteroidogenic factor-1 (SF-1), and anti-T-cell immunoglobulin mucin-1. Tissue microarray methodology was used to simulate small image-guided biopsies. Staining extent and intensity were scored semiquantitatively for each antibody. In comparing different intensity thresholds required for a positive result, a value of at least 2+ was identified as optimal for diagnostic sensitivity and specificity. The authors found the following to have the greatest potential use for distinguishing adrenal cortical lesions from metastatic CC-RCCs: immunoreactivity for the adrenal cortical antigens SF-1 (86 percent adrenal; zero percent CC-RCC), calretinin (89 percent adrenal; 10 percent CC-RCC), inhibin (86 percent adrenal; nine percent CC-RCC), and melan-A (86 percent adrenal; 10 percent CC-RCC), and for the renal epithelial antigens hKIM-1 (zero percent adrenal; 83 percent CC-RCC), PAX-8 (zero percent adrenal; 83 percent CC-RCC), hepatocyte nuclear factor-1β (zero percent adrenal; 76 percent CC-RCC), epithelial membrane antigen (zero percent adrenal; 78 percent CC-RCC), and carbonic anhydrase-IX (three percent adrenal; 87 percent CC-RCC). The authors concluded that use of the novel renal epithelial markers hKIM-1 (clone AKG7) or PAX-8, or both, and the adrenocortical marker SF-1 in an immunohistochemical panel for distinguishing adrenal cortical lesions from metastatic CC-RCC offers improved diagnostic sensitivity and specificity.

Sangoi AR, Fujiwara M, West RB, et al. Immunohistochemical distinction of primary adrenal cortical lesions from metastatic clear cell renal cell carcinoma: a study of 248 cases. Am J Surg Pathol. 2011;35:678–686.

Correspondence: Ankur R. Sangoi at asangoi2@yahoo.com
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Eosinophilic gastritis: histopathological characterization and quantification of normal gastric eosinophil content Eosinophilic gastritis: histopathological characterization and quantification of normal gastric eosinophil content

Limited information is available regarding normal eosinophil counts in the gastric mucosa. Therefore, the authors conducted a study to evaluate the histopathology of 60 patients whose biopsies showed increased eosinophils in this location. The authors also investigated the eosinophil content in gastric biopsies from normal control subjects matched for age, gender, and zip code, as well as from patients with Helicobacter pylori gastritis and patients with Crohn’s disease. Eosinophils were counted in five random high-power fields and reported in eosinophils/mm2. The authors also evaluated involvement of the muscularis mucosae or submucosa, sheets of eosinophils, and infiltration of the gastric epithelium. The median eosinophil count in the study patients was 539 eosinophils/mm2 (mean ± standard deviation [SD], 653±418 eosinophils/mm2; range, 127–2,108). Sheets of eosinophils were seen in 38 patients, and 27 showed involvement of the muscularis mucosae or submucosa. Seven patients did not have epithelial infiltration by eosinophils, whereas 34 were tallied as rare and 19 were scored as abundant. No study patient had lack of evidence of H. pylori. The mean eosinophil count for the 135 normal controls was 15.5±16.8 SD eosinophils/mm2 (range, 0–110). In the 93 controls with H. pylori gastritis, the mean eosinophil count was 25±32.6 SD eosinophils/mm2 (range, 0–219). The eosinophil count was 31.4±44.4 SD eosinophils/mm2 (range, 0–203) for the 53 controls with Crohn’s disease. No significant differences were noted between the counts in biopsies from the antrum and corpus, and no significant variations were noted by age, geographic location, or season. This study confirms that, in the United States, normal gastric eosinophilic counts are usually less than 38 eosinophils/mm2. The authors recommend histological eosinophilic gastritis for the diagnosis of gastric biopsies that show an average density of at least 127 eosinophils/mm2 (or at least 30 eosinophils per high-power field) in at least five high-power fields in the absence of known associated causes of eosinophilia.

Lwin T, Melton SD, Genta RM. Eosinophilic gastritis: histopathological characterization and quantification of the normal gastric eosinophil content. Mod Pathol. 2011;24(4):556–563.

Correspondence: Dr. R. M. Genta at robert.genta@utsouthwestern.edu
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Anatomic pathology abstracts editors: Michael Cibull, MD, professor and vice chair, Department of Pathology and Laboratory Medicine, University of Kentucky College of Medicine, Lexington; Melissa Kesler, MD, and Rouzan Karabakhtsian, MD, assistant professors of pathology and laboratory medicine, University of Kentucky College of Medicine; and Megan Zhang, MD, visiting fellow, Division of Dermatopathology, University of California, San Francisco.